Br J Nutr. 2020 May 4:1-29. doi: 10.1017/S0007114520001506. [Epub ahead of print]
The purpose of this study was to compare next-morning responses of resting metabolic rate (RMR) and appetite to pre-sleep consumption of casein protein (CP) in pre and postmenopausal women. The study was a randomized, crossover, double-blind, placebo-controlled trial. Seven sedentary premenopausal (age: 19.9 (SD 1.2) years, BMI: 23.1(SD 2.6) kg/m2) and seven sedentary postmenopausal (age: 56.4 (SD 4.9) years, BMI: 26.3 (SD 3.5) kg/m2) women participated. During visit one, anthropometrics and body composition were measured. Following visit one, subjects consumed either CP (25g) or placebo (PL) ≥2h after their last meal and ≤30min prior to sleep on the night before visits two and three. Visits two and three occurred ≥one week after visit one and were 48h apart. During visits two and three, RMR (VO2), respiratory exchange ratio (RER), and appetite were measured via indirect calorimetry and visual analogue scale, respectively. Anthropometrics and body composition were analyzed by one-way analysis of variance (ANOVA). RMR and measures of appetite were analyzed using a 2×2 (menopause status × CP/PL) repeated measures ANOVA. Significance was accepted at p≤0.05. RMR was significantly lower in postmenopausal compared to premenopausal women under both conditions (p=0.003). When consumed pre-sleep CP did not alter RMR, RER, or appetite compared to PL when assessed next-morning in pre and postmenopausal women. These data contribute to growing evidence that pre-sleep consumption of protein is not harmful to next-morning metabolism or appetite. In addition, these data demonstrate that menopause may not alter next-morning RMR, RER, or appetite after pre-sleep consumption of CP.